docs: def tool(_progname=sys.argv[0],
           _argv=sys.argv[1:],
           _syspath=sys.path,
           _findMachines=findMachines,
           _print=print):
      """
      Entry point for command line utility.
      """
  
      DESCRIPTION = """
      Visualize automat.MethodicalMachines as graphviz graphs.
      """
      EPILOG = """
      You must have the graphviz tool suite installed.  Please visit
      http://www.graphviz.org for more information.
      """
      if _syspath[0]:
          _syspath.insert(0, '')
      argumentParser = argparse.ArgumentParser(
          prog=_progname,
          description=DESCRIPTION,
          epilog=EPILOG)
      argumentParser.add_argument('fqpn',
                                  help="A Fully Qualified Path name"
                                  " representing where to find machines.")
      argumentParser.add_argument('--quiet', '-q',
                                  help="suppress output",
                                  default=False,
                                  action="store_true")
      argumentParser.add_argument('--dot-directory', '-d',
                                  help="Where to write out .dot files.",
                                  default=".automat_visualize")
      argumentParser.add_argument('--image-directory', '-i',
                                  help="Where to write out image files.",
                                  default=".automat_visualize")
      argumentParser.add_argument('--image-type', '-t',
                                  help="The image format.",
                                  choices=graphviz.FORMATS,
                                  default='png')
      argumentParser.add_argument('--view', '-v',
                                  help="View rendered graphs with"
                                  " default image viewer",
                                  default=False,
                                  action="store_true")
      args = argumentParser.parse_args(_argv)
  
      explicitlySaveDot = (args.dot_directory
                           and (not args.image_directory
                                or args.image_directory != args.dot_directory))
      if args.quiet:
          def _print(*args):
              pass
  
      for fqpn, machine in _findMachines(args.fqpn):
          _print(fqpn, '...discovered')
  
          digraph = machine.asDigraph()
  
          if explicitlySaveDot:
              digraph.save(filename="{}.dot".format(fqpn),
                           directory=args.dot_directory)
              _print(fqpn, "...wrote dot into", args.dot_directory)
  
          if args.image_directory:
              deleteDot = not args.dot_directory or explicitlySaveDot
              digraph.format = args.image_type
              digraph.render(filename="{}.dot".format(fqpn),
                             directory=args.image_directory,
                             view=args.view,
                             cleanup=deleteDot)
              if deleteDot:
                  msg = "...wrote image into"
              else:
                  msg = "...wrote image and dot into"
              _print(fqpn, msg, args.image_directory)